I have an Oookworks solo floor of chikara (sp?) nylon with 10 cm. bathtub sides that stay up at all times. Simple to clip to the mid stakes, and at 3.8 oz., ill never use polycro again. I also have a bivy (Borah) I use for colder nights but I have never found I needed anything for rain. For reference, I am using a duomid.

Note: Last month ookworks had several similar to my floor made up ready for no wait sale on the site. I would look them up, I've been very happy. For more money, Zpacks has you covered too.

The zpacks groundsheet should work really well in the solomid. I also have a borah bivy that has worked great under my solomid. Either would do the job but the bivy would add more weight and some warmth. I think either way, I would want some protection up the sides of my sleeping bag.

I spent a very rainy night at Pt. Reyes last winter under my solomid with just a sheet of polycryo. I got splash around the edges and my bag did get wet. I got wet enough where I would not want to spend another rainy night under that shelter without a bivy or bathtub floor. Just for reference, I am also 6'4, 200 lbs. So I am pushing the limits of being comfortable in this shelter.

if it's a solo mid- I prefer a bivy for possible splash, a larger mid w/ more coverage I'm comfortable w/ just a ground cloth (or an inner if there are bugs to contend w/)

I've had good luck w/ Tyvek for ground cloth- stuff is amazingly tough and no overly slippery (albeit it's heavier than polycro); I grommet the corners and use a small diameter shock cord to secure the corners to the mid

A couple of years ago I decided that a pyramid tarp and a light bivy is the most versatile shelter solution, and it's what i use in my DuoMid With the bivy you don't need a groundsheet. You can find 5oz or 6oz bivies that are bug-proof for bug season- lighter than an innernet.

With my DuoMid, I used a bivy. However, I also used a groundsheet when I was expecting truly wet conditions because the condensation from the wet ground can be significant. My bivy was only water resistant, however.

I use a MLD superlight bivy with the bug head covering in my Duo and Cricket. (If I expect really bad bug situation, I'll use an inner net). The bivy protects from wet ground, splash, wind under the edges of the shaped tarp, and bugs. What more could I ask?

Dave's use of a ground sheet under the bivy when expecting really wet conditions makes sense. It's not a situation I encounter much in the southern Sierras and transverse ranges.

The "problem" is that I using a MLD eVent Soul Bivy, which I love and has been holding up great since 2008, but it is 13 oz.

Add a 15 oz MLD Solo Mid, I am pushing into the weight of a Tarptent Notch.

If I had your bivy, I would come out great with that combo, but I am not willing to give up my current bivy....too much invested into it in terms of money and it is just great.

It does have a silnylon 2.0 floor, which is pretty waterproof, but might wet out after long periods of time on really damp ground.

Learning lots here about how considering "one" change can effect the whole balance of gear that I am using.

My setup now if great for the Sierras, but if I wanted to head to the Pacific North West, I have to consider having more protection from rain.

I like the flexibility of just using a bivy to sleep out under the stars and in small spots that might not allow a tent/mid/tarp and then using the Mid with the bivy when things get bad, but I do have to question if a tarptent would be better.

I do have a Contrail, which I have not used in years, since going to the tarp and bivy.....

Just mental games to think about between trips.

Again, appreciate the advice from everyone.

Ultimately, in very rainy situtations, sounds like a mid, bivy, and groundsheet might be in order....but better to carry some extra weight vs. being miserably wet.